Remove excess dnl from m4sh.

Remove excess dnl from m4sh.

* lib/m4sugar/m4sh.m4 (_AS_DETECT_BETTER_SHELL, _AS_PREPARE)
(_AS_SHELL_FN_WORK, _AS_SHELL_SANITIZE, AS_IF, _AS_ECHO_LOG)
(AS_MESSAGE, AS_ERROR, AS_BASENAME, _AS_BASENAME_PREPARE)
(_AS_DIRNAME_EXPR, AS_DIRNAME, _AS_DIRNAME_PREPARE, AS_ECHO)
(AS_ECHO_N, AS_TEST_X, AS_EXECUTABLE_P, _AS_ME_PREPARE)
(_AS_LINENO_PREPARE, AS_LN_S, AS_MKDIR_P, _AS_PATH_WALK)
(AS_SET_CATFILE, AS_HELP_STRING, AS_TMPDIR, AS_VERSION_COMPARE)
(_AS_TR_SH_PREPARE, AS_TR_SH, _AS_TR_CPP_PREPARE, AS_TR_CPP)
(_AS_TR_PREPARE, AS_VAR_APPEND, AS_VAR_PUSHDEF)
(AS_INIT_GENERATED): Use fewer dnl in m4sh macro bodies.

Signed-off-by: Eric Blake <ebb9@byu.net>